In some medical imaging applications, images from different sources, which are generated using multiple modalities, are registered with one another and displayed. For example, U.S. Pat. No. 5,568,384, whose disclosure is incorporated herein by reference, describes a method for synthesizing 3-D multimodality image sets into a single composite image. Surfaces are initially extracted from two or more different images to be matched using semi-automatic segmentation techniques. The surfaces are represented as contours with common features to be matched. A matching process involves searching the multi-parameter space and adjusting a surface or surfaces to find the best fit among them. Makela, et al., survey methods of image registration in “A Review of Cardiac Image Registration Methods,” IEEE Transactions on Medical Imaging 21:9 (September 2002), pages 1011-1021, which is incorporated herein be reference.
Aylward, et al., describe methods for processing of tubular objects in medical images in U.S. Pat. No. 6,690,816 and in “Registration and Analysis of Vascular Images,” International Journal of Computer Vision 55:2-3 (November-December 2003), pages 123-138, both of which are incorporated herein by reference. They point out that registration of tubular objects in multi-dimensional images may be helpful in medical imaging applications. This sort of tubular object registration aligns the image elements of tubular objects between a source image and a destination image, which may be produced using different image modalities. The patent gives an example of the registration of pre-operative CT or MR data with intra-operative ultrasound data for radio-frequency ablation treatment of liver lesions.